There are available on the market various air-splicing devices for knot-free joining of filament yarns such as the AirSplicer™-17-2 and the AirSplicer™-40-2, both of Heberlein Fiber Technology, Inc., 9630 Wattwil (CH). Whereas glass fiber rovings are mentioned as a possible application of the AirSplicer™-40-2, the results that may be achieved so far are not satisfactory. In fact, tests have revealed that the splice joint of two glass roving strands may be of poor quality in the terms of strength; in a typical application the strength of the splice joint was tested to be only about 35% of the strength of the regular roving strands.
In addition to the prior art discussed above, there are various patent publications relating to air-splicing devices for splice-connecting threaded filament yarns. Typically, the respective devices comprise one splice chamber similar as it applies to the above mentioned prior art devices. However, there are also disclosed air-splicing devices having two splice chambers arranged in series (e.g. U.S. Pat. No. 4,292,796, GB 956992, and DE 4226025). But again, in spite of glass fiber filament yarns being mentioned in German Letters patent 4226025, these devices do not perform well in glass fiber rovings related applications.